An internal gear pump (trochoid pump) is a pump that has an outer rotor and an inner rotor, which have trochoid teeth profiles and which are accommodated in a sealed state within a casing; the inner rotor, which is secured to a drive shaft, and the outer rotor rotating in association with rotation of the drive shaft, and acting so as to take in and eject a liquid. Specifically, the internal gear pump has the following structure. The trochoid is constituted by outer teeth of the inner rotor meshing with inner teeth of the outer rotor, and the inner rotor being rotatably accommodated within the outer rotor in a state of eccentricity. At intervals between dividing points when the rotors come into contact with one another, volume chambers are formed at the intake side and the ejection side, according to the direction of rotation of the trochoid. When the drive shaft rotates and the inner rotor rotates, the outer teeth mesh with the inner teeth of the outer rotor, thereby causing the outer rotor to turn in unison in the same direction. Liquid is taken in from the intake port into the intake-side volume chamber, which, due to this rotation, has expanded in volume and reached negative pressure. As this intake-side volume chamber, due to rotation of the trochoid, decreases in volume and changes to an ejection-side volume chamber, the liquid taken in is ejected therefrom to an ejection port. A liquid intake nozzle is provided as a communicating passage through which the liquid is supplied to the intake-side volume chamber, and the tip of the nozzle is immersed in a liquid reservoir.
One known internal gear pump of this type is that disclosed, for example, in Patent Document 1. Patent Document 1 discloses a transverse internal gear pump installed in a transverse orientation (Patent Document 1, FIGS. 1, 3), and a vertical internal gear pump installed in a vertical orientation (Patent Document 1, FIG. 4), as configurations in which a pump is installed. In the case of a transverse type, the drive shaft of the pump is in a transverse orientation, and the trochoid rotation surfaces are surfaces that are approximately parallel to the vertical direction, whereas in the case of the vertical orientation, the drive shaft of the pump is oriented on the vertical, and the trochoid rotation surfaces are surfaces that are approximately perpendicular to the vertical direction. Here, because it is necessary for the tip of the liquid intake nozzle to be immersed below the liquid surface of the liquid, such as lubricating oil, held in the liquid reservoir, it is necessary to extend the nozzle downward in the vertical direction. For this reason, in the vertical orientation, the liquid intake nozzle is arranged approximately perpendicular to the trochoid rotation surfaces (approximately parallel to the drive shaft), and in the transverse orientation, is arranged non-perpendicular to the trochoid rotation surfaces (non-parallel to the drive shaft).
In Patent Document 1, as transverse internal gear pumps in particular, there are proposed units having a intake nozzle and a pump cover linked thereto, at least one of the intake nozzle and a pump cover comprising a thermoplastic plastic material, where (1) the intake nozzle and the pump cover are secured by plastic working, or (2) the intake nozzle and the pump cover are integrally molded by pressing.